add more safeguarding
add more safeguarding

git-svn-id: 255fdcdd65affe1d42edbf9640002b17f07b9540@1829 b426a367-1105-0410-b9ff-cdf4ab011145

geographika/OWSLib,datagovuk/OWSLib,b-cube/OWSLib,bird-house/OWSLib,ocefpaf/OWSLib,geopython/OWSLib,dblodgett-usgs/OWSLib,datagovuk/OWSLib,tomkralidis/OWSLib,menegon/OWSLib,datagovuk/OWSLib,jaygoldfinch/OWSLib,jachym/OWSLib,daf/OWSLib,kalxas/OWSLib,jaygoldfinch/OWSLib,KeyproOy/OWSLib,Jenselme/OWSLib,robmcmullen/OWSLib,gfusca/OWSLib,daf/OWSLib,kwilcox/OWSLib,daf/OWSLib,QuLogic/OWSLib,mbertrand/OWSLib,JuergenWeichand/OWSLib